The PR1 range of thyristor stacks provides full seamless control of single phase resistive loads. Signal control is by a DC signal. These burst firing control stacks use fast pulse zero volts switching technology, to minimise flicker and eliminate RFI problems. They also incorporate an automatic-reset over temperature protection trip, integral semiconductor fuses and heatsink, all enclosed. The three models in this build include the smaller 1.5kW model and the 3kW and 6kW models in the larger enclosure. All have easy access to signal & power terminals for simple installation.